Timeseries of marginal sea ice zone
Approximation of sea ice concentration timeseries by monotonos function.
Use an argument (date) when monotonuos function intersects sia ice concentration 15% constant value.
Single-layered map instead of multi-layered map of timeseries
One map instead of map series, but only ice extent by sea ice concentration level 15% is figured.
Contouring displaying as additional layer
Isochromes are better for visual analysis of phenology rate. Higher density of isochrones means slow rate of retreat or advance. Slow rate of sea ice retreat doesn’t force high locomotion near ice edge.
Smoothing of input phenology maps is desirable.
Distance between contour lines per fixed time interval
Slope/elevation GIS tools are used to generate rate maps with distinguish that day/meter not meter/meter relation is used to calculate slope.
Rate and direction of ice status change
Arrows are normal to isochrones.
Rates of sea ice disappearance in 2016-2019
Longterm (2003-2019) mean, variability and trends of sea ice disappearance rate
Longterm (2004-2019) mean, variability and trends of sea ice appearance rate
Length of ice-covered period based on sea ice disappearance and appearance dates. Contour is isochrone of 180 days (Gormezano and Rockwell, 2015)
Spatial profile: ice habitat decreasing,
or temporal profile: Ice-covered season shortening
Extent of annual ice expands northern waters with insignificant change of ice edge rate (km/day).
Rate of sea ice appearance is higher then rate of sea ice disappearance.
Gormezano LJ, Rockwell RF. 2015. The energetic value of land-based foods in western Hudson bay and their potential to alleviate energy deficits of starving adult male polar bears. In: Dias J. M. (Ed) PLOS ONE, 10(6): e0128520. Public Library of Science (PLoS). 10.1371/journal.pone.0128520.